Every once in a long while, something happens in New York that restores your faith in humanity:

Who has ridden along New York’s 656 miles of subway lines and not wondered: “What if I fell to the tracks as a train came in? What would I do?” And who has not thought: “What if someone else fell? Would I jump to the rescue?”

Mr. Autrey was waiting for the downtown local at 137th Street and Broadway in Manhattan around 12:45 p.m. He was taking his two daughters, Syshe, 4, and Shuqui, 6, home before work.

Nearby, a man collapsed, his body convulsing. Mr. Autrey and two women rushed to help, he said. The man, Cameron Hollopeter, 20, managed to get up, but then stumbled to the platform edge and fell to the tracks, between the two rails.

The headlights of the No. 1 train appeared. “I had to make a split decision,” Mr. Autrey said.

So he made one, and leapt.

Mr. Autrey lay on Mr. Hollopeter, his heart pounding, pressing him down in a space roughly a foot deep. The train’s brakes screeched, but it could not stop in time.

Five cars rolled overhead before the train stopped, the cars passing inches from his head, smudging his blue knit cap with grease. Mr. Autrey heard onlookers’ screams. “We’re O.K. down here,” he yelled, “but I’ve got two daughters up there. Let them know their father’s O.K.” He heard cries of wonder, and applause.